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In this study, we aimed to compare epiphytic diatom species diversity, which identified at two different periods (July 1998 - June 1999 and June 2014 - May 2015) at littoral zon of Lake Uluabat. 214 taxa were identified belonging to Bacillariophyta division during the study period of July 1998 to June 1999, while 86 taxa at June 2014 - May 2015. Cocconeis placentula var. lineata (Ehrenberg) van Heurck, Nitzschia amphibia Grunow and Rhoicosphaenia abbreviata (C.Agardh) Lange-Bertalot were the most important taxa in terms of dominancy of relative abundance and repetition rates at both two study periods. When comparing these two studies, taxa richness of epiphytic diatom flora has been found to be reduced by years. Increasing pollution load and eutrophication level at the lake due to years, thought to be the cause of the decline of epiphytic diatom taxa richness.

This study was carried out at three stations of Lake Uluabat betweenMarch 2006 and January 2007. Composition, density and spatio-temporalvariations of phytoplankton of Lake Uluabat were investigated. During the studyperiod, a total of 169 taxa were identified. 56 taxa belong to Bacillariophyta,51 to Chlorophyta, 25 to Cyanobacteria, 19 to Euglenophyta, 7 to Miozoa, 6 toCharophyta and 5 to Ochrophyta. The results of this study were compared withthe previous studies, indicated that the phytoplankton taxa richness wereapproximately reduced by half in Lake Uluabat. According to RDA analysis, watertemperature and nitrate nitrogen were the most important physicochemicalparameters that affect species composition, density and spatio-temporal variationsof phytoplankton of Lake Uluabat. The phytoplankton composition of Lake Uluabatindicated that the trophic state of lake was eutrophic., Bu çalışma Uluabat Gölünde Mart 2006 – Ocak 2007 tarihlerinde üçistasyonda gerçekleştirilmiştir. Uluabat Gölü fitoplanktonunun kompozisyonu,yoğunluğu, zamansal ve mekansal değişimleri incelenmiştir. Çalışma döneminde169 takson tespit edilmiştir. Bu taksonların 56’sı Bacillariophta, 51’iChlorophyta, 25’i Cyanobacteria, 19’u Euglenophyta, 7’si Miozoa, 6’sıCharophyta ve 5’i Ochrophyta’ya aittir. Bu araştırma sonuçları daha öncegerçekleştirilmiş çalışmalar ile karşılaştırıldığında, Uluabat Gölü takson zenginliğininyaklaşık yarı yarıya azaldığı tespit edilmiştir. RDA analizine göre susıcaklığı ve nitrat azotunun Uluabat Gölü fitoplanktonunun tür kompozisyonu,yoğunluğu ve zamansal-mekansal değişimlerini etkileyen en önemli fizikokimyasalparametreler olduğu tespit edilmiştir. Fitoplankton kompozisyonuna göre UluabatGölü’nün ötrofik karakterde olduğu belirlenmiştir.

Patterns of epilithic diatom species distribution in relation to environmental variables from 12 sampling sites on the main stream and some of its tributaries in the Nilufer Stream Basin were determined using multivariate statistical techniques. The stream basin has been heavily influenced by anthropogenic effects. The upper part of the basin that is distant from pollution sources mostly has a spring water quality, while the lower part where the stream flows through the urban area and receives domestic and industrial wastewater has a quite low quality. Ordination techniques using both diatom taxa and 21 environmental variables revealed non-to slightly polluted upper basin sites and highly polluted lower basin sites along the stream. The results showed that the stream catchment is polluted gradually from upstream to downstream and that most of the downstream sites have very low water quality especially in summer months. A total of 134 epilithic diatom taxa belonging to 50 genera were recorded for 12 sample sites. Partial CCA results indicated that water temperature (T), discharge (Q), and total phosphorus (TP) were the most important variables affecting the distribution of diatom species. Unpolluted or slightly polluted upper basin sites were dominated by Achnanthidium minutissimum, Cocconeis placentula var. euglypta, Gomphonema olivaceum, and Navicula tripunctata. Highly polluted lower basin sites were characterized by high levels of organic and inorganic matters and low dissolved oxygen (DO) values. Species widespread in the highly polluted lower basin sites such as Nitzschia umbonata, Nitzschia amphibia, Nitzschia capitellata, Nitzschia palea, Nitzschia paleacea, Luticola mutica, and Stephanodiscus niagarae were mostly related to pollution indicator variables such as ammonium nitrogen (NH4(+)-N), sodium (Na+), total phosphorus (TP), and total organic matter (TOM).

Three hundred and thirty-one phytoplankton taxa were identified from Lake Uluabat over a 12-month period in 1998–1999. Phytoplankton richness varied between 35 and 79 taxa, and the Shannon-Wiener diversity index range was 1.574–3.151. Lake Uluabat was characterized by a high variety of Bacillariophyta (152 taxa), Chlorophyta (89 taxa), and Cyanobacteria (42 taxa). Total diversity was strongly correlated with dissolved oxygen and pH, but total species richness and total density were mostly influenced by temperature and Secchi depth. The lake supported a dynamic phytoplankton community through most months of the year.

Nilüfer Stream is an important water source in the industrial and metropolitan city of Bursa, Turkey. The stream catchment has been influenced by high human impact. The downstream receives sewage water from households and industry, whereas the headwater of the stream has a source of high-quality drinkable water. In this paper, abundances of epipelic diatom taxa, faecal coliforms (FC), total coliforms (TC) and total bacteria (TB) were studied in relation to measured environmental variables (T, pH, DO, BOD(5), EC, TDS) for the period July 1997 to June 1998 at six stations in the heavily polluted Nilüfer Stream catchment. It is observed that the physicochemical variables and bacterial abundances varied seasonally at all stations, and the level of pollution reached at its highest point in the summer. The results of Kruskal-Wallis and one-way ANOVA indicated that DO gradually decreased, whereas BOD(5), EC, TDS, TB, FC and TC gradually increased from upstream to downstream. The ordination method of Principal Component Analysis (PCA) was carried out for both biologic and physicochemical variables, and the results were supported by the former statistical procedures. The frequency of occurrence of dominant diatoms was examined in relation to the spatial variations in chemical constituents. Both diatoms and bacteria showed strong correlations with the measured physicochemical variables. In Canonical Correlation Analysis (CANCORR) measures of bacterial abundances also displayed strong correlations with abundances of 11 diatom taxa. The results showed that the stream catchment is polluted gradually from upstream to downstream. In addition, pollution load in the stream catchment has been gradually increased, compared with recent years. Urbanisation and industrialisation of the city have affected increasing pollution in Nilüfer Stream. The results also indicated that diatoms are not affected by environmental variables such as bacteria. Bacteria are more sensitive to organic pollution, while diatoms are indicators of different environmental conditions.